Liquid crystal display device

ABSTRACT

A liquid crystal display device in which alignment control in a vertical-alignment-type liquid crystal layer is excellent at a side portion or a corner portion of a pixel electrode. The liquid crystal display device includes a pixel electrode including openings of slits as an alignment control mechanism, a common electrode including linear protrusions as an alignment control mechanism, the electrodes opposed to each other, and a vertical-alignment-type liquid crystal layer sandwiched between the electrodes, wherein the linear protrusion is placed at a position where the linear protrusion controls alignment in the liquid crystal layer inside a position where an oblique electric field generated at the edge of an corner portion of the pixel electrode at the time when a voltage is applied between the electrodes controls the alignment in the liquid crystal layer.

This application is a Continuation of Ser. No. 12/441,445, filed Oct.22, 2009 now U.S. Pat. No. 8,159,640, which is a 371 (national stage) ofPCT/JP2007/057467, filed 3 Apr. 2007, which designates the U.S. andclaims priority to Japanese Application No. 2006-256781, filed 22 Sep.2006, the entire contents of each of which are all hereby incorporatedby reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device using avertical alignment mode which has excellent image display quality.

2. Description of the Related Art

In recent years, a liquid crystal display device is in widespread use asa display of a household electrical appliance such as a personalcomputer and a television set. In the liquid crystal display device, aliquid crystal panel is used which includes two glass substrates betweenwhich a liquid crystal is filled in a space surrounded by a sealingmember.

For the liquid crystal display device as described above, a liquidcrystal display device using a vertical alignment mode is commerciallypractical, in which a liquid crystal layer possessing negativedielectric anisotropy is interposed between an opposed glass substratepair such that liquid crystal molecules are aligned vertically, and whena voltage is applied to the liquid crystal layer, the liquid crystalmolecules are controlled to be aligned in a plurality of inclineddirections relative to the glass substrates.

In this liquid crystal display device using the vertical alignment mode,the liquid crystal molecules are aligned vertically relative to theopposed glass substrate pair in a state where no voltage is appliedthereto which defines a non-driven state, so that light which passesthrough the liquid crystal layer has its polarization plane littlechanged. Hence, by providing and arranging polarizing plates in theposition of crossed Nicols on and under the glass substrates, blackdisplay can be achieved almost perfectly in the state where no voltageis applied thereto, and thereby a high-contrast image is obtained.

There arises a problem of viewing angle dependency in this liquidcrystal display device using the vertical alignment mode, a similarproblem arising also in a conventional liquid crystal display deviceusing a TN mode; however, solutions to the problem are found as follows.Since, in order to improve viewing angle characteristics in display, itis effective to create a plurality of domains in one pixel forcontrolling liquid crystal molecules aligned in a vertical direction tobe aligned in a plurality of inclined directions that are different fromone domain to another relative to the vertical direction, protrusionsare provided on an alignment layer or openings are provided in anelectrode in the liquid crystal display device in order to create thesedomains.

As shown in FIG. 6, vertical-alignment-type liquid crystal molecules 53which possess negative dielectric anisotropy tend to get vertical to anelectric field direction 54 when a voltage is applied between electrodes51 and 52. In this case, azimuthal directions of the liquid crystalmolecules 53 become at random as shown in FIG. 6 if there is nothing tocontrol the azimuthal directions. In contrast, the azimuthal directionsare determined if there provided protrusions 55 and openings 57 as shownin FIG. 7. In this case, when a voltage is applied, the liquid crystalmolecules 53 in the vicinities of the protrusions 55 and the openings 57first start to incline before the liquid crystal molecules 53 in theother regions start to incline, and then the liquid crystal molecules 53in the other regions start to tilt as if propagating through theregions, whereby the azimuthal directions of the aligned liquid crystalmolecules 53 are controlled. Besides, in FIG. 7, a reference numeral 58indicates equipotential lines at the time when a voltage is applied, anda reference numeral 59 indicates an oblique electric field (a fringefield).

Next, a description of a specific example of use of the above-describedalignment control mechanisms will be given. As shown in FIG. 8, on anarray substrate, a pair of gate bus lines 11 and a pair of source buslines 12 which are perpendicular to each other are arranged in a gridpattern, and a pixel electrode 51 is provided in a pixel regionsurrounded by the gate bus lines 11 and the source bus lines 12. In thepixel electrode 51, openings 57 of slits are formed to extend in anoblique direction. The openings 57 are provided and arranged to generatean oblique electric field (a fringe field) at the time when a voltage isapplied and to control liquid crystal molecule alignment in order toimprove viewing angle characteristics as mentioned above. The openings57 which are oblique at a given angle are arranged to be verticallysymmetrical in each pixel electrode 51 as shown in FIG. 8.

Under the common electrode 52 (not shown in FIG. 8), linear protrusions55 a to 55 c are provided. The linear protrusions 55 a to 55 c which areoblique at a given angle are arranged to be vertically symmetrical ineach pixel electrode 51 in FIG. 8, and are placed at substantiallycenter positions between the adjacent openings 57. The linearprotrusions 55 a to 55 c are provided and arranged to align liquidcrystal molecules in given inclined directions relative to the verticaldirection in order to improve viewing angle characteristics.

The widths of liquid crystal domains which are defined by the openings57 and the linear protrusions 55 a to 55 c are set to be optimumconsidering a vertical-alignment-type liquid crystal layer to be used, avoltage to be applied at the time of the lowest tone or a voltage to beapplied at the time of the highest tone (see Japanese Patent ApplicationUnexamined Publication No. 2002-229038).

The pixel electrode 51 having a substantially rectangular shape has fourcorner portions 51 b, 51 c, 51 d and 51 e, and among them, the upperleft corner portion 51 b, the upper right corner portion 51 d and thelower right corner portion 51 e where a TFT 13 is not located arerounded. The rounding is made in order to adjust the areas of the cornerportions 51 b, 51 d and 51 e to the area of the lower left cornerportion 51 c with a notch where the TFT 13 is located and adjustparasitic capacitances of the pixel electrode 51 and the bus lines 11and 12. However, as a result of setting the widths of the liquid crystaldomains defined by the openings 57 and the linear protrusions 55 a to 55c to be optimum, the upper right linear protrusion 55 c and the lowerright liner protrusion 55 c could be placed outside the corner portions51 d and 51 e respectively.

FIG. 9 is a cross-sectional view along the line C-C in FIG. 8. In thiscase, the position where the equipotential lines 58 at the edge of thecorner portion 51 e of the pixel electrode 51 fall down, in other words,the position where the alignment of the liquid crystal molecules 53 iscontrolled by the oblique electric field 59 which is generated at theedge of the corner portion 51 e, is located inside the position wherethe alignment of the liquid crystal molecules 53 is controlled by thelinear protrusion 55 c. Due to this, the azimuthal directions of theliquid crystal molecules 53 are not determined in this range, resultingin poor alignment of the liquid crystal molecules 53. This kind of pooralignment is visually perceived as irregular luminance on a liquidcrystal display screen, which becomes a cause of loss of displayquality.

SUMMARY OF THE INVENTION

In order to overcome the problems described above, a preferredembodiment of the present invention provides a liquid crystal displaydevice in which alignment control in a vertical-alignment-type liquidcrystal layer is excellent at a side portion or a corner portion of apixel electrode.

To achieve the objects and in accordance with the purpose of the presentinvention, a liquid crystal display device includes a pixel electrodeincluding first alignment control mechanisms, a common electrodeincluding second alignment control mechanisms, the pixel electrode andthe common electrode being opposed to each other, and avertical-alignment-type liquid crystal layer which is sandwiched betweenthe pixel electrode and the common electrode, wherein the secondalignment control mechanism in the vicinity of a side portion or acorner portion of the pixel electrode is placed at a position where thesecond alignment control mechanism controls liquid crystal alignment inthe liquid crystal layer inside an edge of the side portion or an edgeof the corner portion of the pixel electrode.

In this case, it is preferable that the second alignment controlmechanism in the vicinity of the side portion or the corner portion ofthe pixel electrode is placed to partially overlap with the side portionor the corner portion of the pixel electrode. Further, it is preferablethat an overlapping width of the second alignment control mechanism withthe side portion or the corner portion of the pixel electrode is 4 μm ormore. Furthermore, it is preferable that the second alignment controlmechanism is placed along the edge of the side portion or the edge ofthe corner portion of the pixel electrode.

In addition, it is preferable that the first alignment controlmechanisms are openings of slits which are formed in the pixelelectrode, and the second alignment control mechanisms are linearprotrusions which are formed on the common electrode.

According to the liquid crystal display device having theabove-described configuration, since the second alignment controlmechanism in the vicinity of the side portion or the corner portion ofthe pixel electrode is placed at the position where the second alignmentcontrol mechanism controls the liquid crystal alignment in the liquidcrystal layer inside the edge of the side portion or the edge of thecorner portion of the pixel electrode, the alignment control in theliquid crystal layer becomes excellent at the side portion or the cornerportion of the pixel electrode.

In this case, when the second alignment control mechanism in thevicinity of the side portion or the corner portion of the pixelelectrode is placed to partially overlap with the side portion or thecorner portion of the pixel electrode, an aperture ratio becomes highercompared with a case where the second alignment control mechanism isentirely placed inside the side portion or the corner portion of thepixel electrode. Further, when the overlapping width of the secondalignment control mechanism with the side portion or the corner portionof the pixel electrode is 4 μm or more, poor alignment is prevented.Furthermore, when the second alignment control mechanism is placed alongthe edge of the side portion or the edge of the corner portion of thepixel electrode, a region can be widened where liquid crystal moleculealignment is controlled inside the edge of the side portion or the edgeof the corner portion of the pixel electrode.

In addition, when the first alignment control mechanisms are theopenings of slits which are formed in the pixel electrode, and thesecond alignment control mechanisms are the linear protrusions which areformed on the common electrode, the first and the second alignmentcontrol mechanisms can be used as a combination which is widely used asan alignment control mechanisms for a vertical-alignment-type liquidcrystal layer in a liquid crystal display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a magnified schematic plan view showing one pixel in a liquidcrystal display device according to a preferred embodiment of thepresent invention.

FIG. 2 is a cross-sectional view along the line A-A in FIG. 1.

FIG. 3 is a cross-sectional view along the line B-B in FIG. 1

FIG. 4 is a table showing relations between overlapping widths W of alinear protrusion with a pixel electrode shown in FIG. 1, and alignmentcontrol in a liquid crystal layer.

FIG. 5 is a magnified schematic plan view showing a modified example ofthe pixel in the liquid crystal display device.

FIG. 6 is a view schematically showing an alignment state of liquidcrystal molecules at the time when a voltage is applied in a case whereno alignment control mechanism is provided.

FIG. 7 is a view schematically showing an alignment state of liquidcrystal molecules at the time when a voltage is applied in a case wherelinear protrusions and openings that define alignment control mechanismsare provided.

FIG. 8 is a magnified schematic plan view showing one pixel in aconventional liquid crystal display device.

FIG. 9 is a cross-sectional view along the line C-C in FIG. 8.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A detailed description of a liquid crystal display device according to apreferred embodiment of the present invention will now be given withreference to the accompanying drawings. FIG. 1 is a magnified schematicplan view showing one pixel in the liquid crystal display deviceaccording to the preferred embodiment of the present invention. FIG. 2is a cross-sectional view along the line A-A in FIG. 1. FIG. 3 is across-sectional view along the line B-B in FIG. 1

As shown in FIG. 2, in a liquid crystal display device 1, a liquidcrystal layer 40 is interposed between a pair of opposed glasssubstrates 10 and 30 (10: the array substrate, 30: the color filtersubstrate), and on the glass substrate 10 which is located lower, pixelelectrodes 17 are arranged in a matrix.

First, a description of the glass substrate (array substrate) 10 isprovided. As shown in FIG. 1, on the periphery of each of the pixelelectrodes 17, a pair of gate bus lines 11 and a pair of source buslines 12 preferably made from aluminum are formed to be perpendicular toeach other. The gate bus lines 11 and the source bus lines 12 cross eachother such that the gate bus lines 11 are located lower than the sourcebus lines 12 at intersection portions thereof, and the gate bus lines 11and the source bus lines 12 are electrically insulated from each otherat the intersection portions.

At the lower-left intersection portion of the gate bus line 11 and thesource bus line 12, a TFT (thin film transistor) 13 that defines aswitching element is provided, to which a gate electrode 11 a thatdefines a part of the gate bus line 11 is connected.

The gate bus line 11 and the gate electrode 11 a are formed in onewiring layer (a first wiring layer). In other words, the gate bus line11 and the gate electrode 11 a are formed by patterning one conductivefilm. The gate bus line 11 and the gate electrode 11 a are coated with agate insulating film 14 preferably made from silicon nitride (see FIG.2).

On the gate insulating film 14, a semiconductor layer (not shown)preferably made from amorphous silicon is formed to be integral with theTFT 13 so as to overlay the gate electrode 11 a. On the gate insulatingfilm 14, a source electrode 13 a and a drain electrode 13 b are formedon both sides of the semiconductor layer on the gate electrode 11 a soas to be spaced apart from each other. The source electrode 13 a isconnected to the source bus line 12, and the drain electrode 13 b isconnected to the pixel electrode 17 via a contact hole 17 a. The sourcebus lines 12, the source electrode 13 a and the drain electrode 13 b areformed in one wiring layer (a second wiring layer), which is not shownin FIG. 2.

The TFT 13 is on/off controlled by a scanning signal voltage provided bythe gate electrode 11 a of the gate bus line 11. A display signalvoltage provided by the source electrode 13 a via the source bus line 12is provided to the pixel electrode 17 via the drain electrode 13 b andthe contact hole 17 a of the pixel electrode 17.

The source bus line 12 and the TFT 13 are coated with an interlayerinsulating film 19 which is formed on the gate insulating film 14. Theinterlayer insulating film 19 is preferably made from a photosensitiveacrylic resin (photosensitive organic film) material, and is interposedbetween the TFT 13 and the first and second wiring layers (the gate busline 11 and the source bus line 12), and the pixel electrode 17 in orderto insulate the electric conductors from each other (see FIG. 2).

On the interlayer insulating film 19, one pixel electrode 17 is formedper pixel region. The pixel electrode 17 is preferably made from atransparent electric conductor such as an ITO (indium-tin oxide)material.

As shown in FIG. 1, the pixel electrode 17 having a substantiallyrectangular shape has four corner portions 17 b to 17 e, and among them,the upper left corner portion 17 b, the upper right corner portion 17 dand the lower right corner portion 17 e where a TFT 13 is not locatedare rounded. In the pixel electrode 17, a plurality of openings 18 ofslits are formed to extend in an oblique direction. The openings 18 areprovided and arranged to generate an oblique electric field (a fringefield) at the time when a voltage is applied and to control liquidcrystal molecule alignment in order to improve viewing anglecharacteristics. In the preferred embodiment of the present invention,the openings 18 which are oblique at a given angle are arranged to bevertically symmetrical in each pixel electrode 17 as shown in FIG. 1. Inaddition, a lower alignment layer 21 is formed on the pixel electrode 17as shown in FIG. 2. The lower alignment layer 21 is preferably made froma polyimide resin.

A description of a method to manufacture the above-described glasssubstrate (array substrate) 10 will be provided. First, a single-layeror multi-layer conductor film made from materials such as tungsten,titanium, aluminum and chromium is formed on the glass substrate 10.This conductor film can be formed by a known method such as sputtering.The formed conductor film is then formed into a predetermined patternpreferably by photolithography. Thus, the gate bus lines 11 and the gateelectrodes 11 a in the predetermined pattern are formed.

Then, the gate insulating film 14 is formed. The gate insulating film 14is preferably made from silicon nitride and is formed preferably by aplasma CVD method. On the insulating film 14, the semiconductor layers(not shown) of the TFTs 13, the source bus lines 12, the sourceelectrodes 13 a and the drain electrodes 13 b are formed.

The semiconductor layers of the TFTs 13 are preferably made from n+ typeamorphous silicon and are formed preferably by a plasma CVD method. Thesource bus lines 12, the source electrodes 13 a and the drain electrodes13 b are formed in the same manner as the gate bus lines 11.

Then, the interlayer insulating film 19 made from a photosensitiveacrylic resin (photosensitive organic film) material is formed, andcontact holes are formed in the formed interlayer insulating film 19preferably by photolithography. On the interlayer insulating film 19,the transparent conductive film made from the ITO material is formedpreferably by sputtering. The formed ITO film is then formed into apredetermined pattern preferably by photolithography. Thus, the pixelelectrodes 17 and the contact holes 17 a in the predetermined patternare formed.

After the pixel electrodes 17 are formed, the lower alignment layer 21is formed. Specifically, a liquid alignment material consisting ofpolyimide or other material is applied preferably by a cylinder printingpress or an inkjet printing press, and is then baked by heating thesubstrate preferably using a baking system. Thus, the solid-state loweralignment layer 21 is formed on the pixel electrodes 17. The glasssubstrate (array substrate) 10 is formed through the processes describedabove.

Next, a description of the glass substrate (color filter substrate) 30will be provided. As shown in FIG. 2, the black matrix 31 is formedunder the glass substrate 30. The areas on the glass substrate 10 wherethe gate bus lines 11, the source bus lines 12 and the TFT 13 are formedare arranged to be shielded from light by the black matrix 31. Under theglass substrate 30, a color layer 32 having one color among red (R),green (G), and blue (B) is formed in each pixel. In the preferredembodiment of the present invention, the red (R), green (G), and blue(B) color layers 32 are repeatedly aligned in order in a horizontaldirection, while the color layers 32 having the same color are alignedin a vertical direction.

Under the color layer 32, a common electrode 33 common to each pixel isformed. The common electrode 33 is also made from a transparent electricconductor such as an ITO material. Under the common electrode 33, linearprotrusions 34 a, 34 b and 34 c are formed. As shown in FIG. 1, thelinear protrusions 34 a to 34 c which are oblique at a given angle arearranged to be vertically symmetrical in each pixel electrode 17. Thelinear protrusions 34 a to 34 c are provided and arranged to alignliquid crystal molecules in given inclined directions relative to thevertical direction in order to improve viewing angle characteristics. Inaddition, under the common electrode 33, an upper alignment layer 36 isformed to cover the linear protrusions 34 a and 34 b as shown in FIG. 2.The upper alignment layer 36 is preferably made from a polyimide resin.

A description of a method to manufacture the above-described glasssubstrate (color filter substrate) 30 will be provided. First, a BMresist (a photosensitive resin composition including a black coloringagent) or other material is applied on the glass substrate 30. Theapplied BM resist is formed into a predetermined pattern preferably byphotolithography. Thus, the black matrix 31 in the predetermined patternis formed.

Then, color inks made of a red, green and blue coloring photoresistmaterials (solutions in which pigments of certain colors are dispersedin photosensitive resins) are applied and formed into a predeterminedpattern preferably by photolithography. Thus, the color layers 32 in thepredetermined pattern are formed. On the color layers 32, thetransparent conductive film made from the ITO material is formed usingsputtering, and thus the common electrode 33 is formed.

Next, a resist (a photosensitive resin composition) or other material isapplied on the common electrode 33. The applied resist is formed into apredetermined pattern preferably by photolithography. Thus, the linearprotrusions 34 a to 34 c in the predetermined pattern are formed.

After the linear protrusions 34 a to 34 c are formed, the upperalignment layer 36 is formed. Specifically, a liquid alignment materialconsisting of polyimide or other material is applied preferably by acylinder printing press or an inkjet printing press, and is then bakedby heating the substrate preferably using a baking system. Thus, thesolid-state upper alignment layer 36 is formed on the common electrode33. The glass substrate (color filter substrate) 30 is formed throughthe processes described above.

The glass substrate (array substrate) 10 and the glass substrate (colorfilter substrate) 30 which have the above-described configurationssandwich the vertical-alignment-type liquid crystal layer 40 possessingnegative dielectric anisotropy. In addition, polarizing plates (notshown) are placed under the glass substrate 10 and on the glasssubstrate 30. Transmission axes of the pair of polarizing plates arearranged to be substantially perpendicular to each other (crossedNicols). The transmission axis of one of the polarizing plates is placedin the direction horizontal to a display surface, and is arranged to beoblique at about 45 degrees with respect to the extending directions ofthe openings 18 of slits and the linear protrusions 34 a to 34 c.

In bonding the glass substrate (array substrate) 10 and the glasssubstrate (color filter substrate) 30 together, a thermal-hardening orultraviolet-cure sealing material and a common transfer material areapplied to the substrate 10 or 30 preferably using a seal patterningdevice. Then, a liquid crystal is dropped filled in a display region onthe substrate 10 or 30 preferably using a liquid crystal drop filldevice, and the substrates 10 and 30 are bonded together in areduced-pressure atmosphere to harden the sealing material. Thus, theliquid crystal display device 1 is prepared.

Next, a description is provided referring to FIG. 3 that is across-sectional view along the line B-B in FIG. 1. As shown in FIG. 3,the linear protrusion 34 c is placed on the common electrode 33 at aposition where the linear protrusion 34 c controls the alignment of theliquid crystal molecules 53 inside a position where the oblique electricfield 59 which is generated at the edge of the corner portion 17 e ofthe pixel electrode 17 at the time when a voltage is applied between theelectrodes 33 and 17 controls the alignment of the liquid crystalmolecules 53, so that the alignment control in the liquid crystal layer40 is more excellent at the corner portion 17 e of the pixel electrode17 than the case as shown in FIG. 9. This is because azimuthaldirections of the liquid crystal molecules 53 of which the alignment iscontrolled by the opening 18 provided in the corner portion 17 ecoincide with those of the liquid crystal molecules 53 of which thealignment is controlled by the linear protrusion 34 c placed inside theedge of the corner portion 17 e without being influenced by the obliqueelectric field 59 generated at the edge of the corner portion 17 e.

In this case, if the linear protrusion 34 c is placed to partiallyoverlap with the corner portion 17 e of the pixel electrode 17, anaperture ratio becomes higher compared with a case where the linearprotrusion 34 c is entirely placed inside the edge of the corner portion17 e. FIG. 4 is a table showing relations between overlapping widths W(μm) of the linear protrusion 34 c with the corner portion 17 e shown inFIG. 1, and evaluations of the alignment observed from a di splayscreen. As shown in the table, when the overlapping width W is 0 μm,poor alignment is caused as described above and is rated as veryunfavorable (X). When the overlapping width W is 2 μm, poor alignment isslightly caused and is rated as unfavorable (Δ). When the overlappingwidth W is 4 μm, 6 μm or 8 μm, no poor alignment is caused and is ratedas favorable (◯), which means favorable alignment with no transmittanceloss. Thus, it is apparent that by securing the overlapping width of 4μm or more, the alignment control in the liquid crystal layer 40 becomesmore favorable.

FIG. 5 is a view showing a modified example of the pixel in the liquidcrystal display device shown in FIG. 1. As shown in FIG. 5, it ispreferable to provide auxiliary portions 35 which extend from the endsof the linear protrusions 34 c in the horizontal direction and thevertical direction in order to widen a region where the alignment of theliquid crystal molecules 53 is controlled inside the edges of the cornerportions 17 d and 17 e of the pixel electrode 17 or in order to improvecapability for the alignment control. By thus placing the linearprotrusions 34 c and the auxiliary portions 35 along the edges of thecorner portions 17 d and 17 e, the alignment control becomes morefavorable.

The foregoing description of the preferred embodiment of the presentinvention has been presented for purposes of illustration anddescription. However, it is not intended to limit the present inventionto the preferred embodiment described herein, and modifications andvariations are possible as long as they do not deviate from theprinciples of the invention. For example, while the configuration inwhich openings of slits and linear protrusions are provided respectivelyto a pixel electrode and a common electrode as alignment controlmechanisms has been described in the above-described preferredembodiment of the present invention, the present invention can be alsoapplied to a configuration in which openings and linear protrusions areprovided to electrodes opposite to the above described configuration. Inaddition, the present invention can be applied to a configuration inwhich openings of slits or linear protrusions are provided to bothelectrodes.

What is claimed is:
 1. A liquid crystal display device comprising: apixel electrode structure comprising a pixel electrode and at least onefirst alignment control mechanism; a common electrode structurecomprising a common electrode and at least one second alignment controlmechanism, the pixel electrode and the common electrode being opposed toeach other with a liquid crystal layer sandwiched between at least thepixel electrode and the common electrode, wherein the pixel electrodecomprises at least one chamfered and/or rounded corner portion so as todefine a non-right-angle-corner portion, the second alignment controlmechanism in the vicinity of the non-right-angle-corner portion of thepixel electrode is placed at least at a position where the secondalignment control mechanism controls liquid crystal alignment in theliquid crystal layer inside an edge of the non-right-angle-cornerportion of the pixel electrode, and the second alignment controlmechanism partially overlaps with and extends along an edge of thenon-right-angle-corner portion of the pixel electrode, wherein anoverlapping width of the second alignment control mechanism with saidedge of the non-right-angle-corner portion of the pixel electrode is atleast 4 μm.
 2. The liquid crystal display device of claim 1, wherein theliquid crystal layer is a vertical-alignment-type liquid crystal layer.3. The liquid crystal display device of claim 1, wherein the firstalignment control mechanism comprises openings and/or slits which areformed in the pixel electrode, and the second alignment controlmechanism comprises protrusions supported by the common electrode.